1. Field of the Invention
This invention relates to a method for producing a stream of ionic aluminum, specially intended, for example, for aluminum ion implantation in the microelectronics industry, as well as to a generator implementing the method.
2. Discussion of the Related Art
Ion stream generators are known which include an ionization chamber, a ionization gas inlet line to the ionization chamber, an auxiliary gas inlet line to the ionization chamber, an electrode facing into the ionization chamber and being supplied a sufficiently large current to produce ionization of matter present in the ionization chamber by thermoelectronic effect and consequent formation of a plasma, and an opening in the ionization chamber wherethrough the plasma can be taken out. Such a construction corresponds, for example, to that of the Eaton Nova NV 10-80 apparatus.
The operation of a generator of that kind includes bombarding the ionization gas with an electron flow generated by thermoelectronic effect from the electrode, as supplied with suitably large currents. In this way, a plasma comprising ions at a high temperature is formed within the ionization chamber.
With a generator as outlined above, a plasma stream can be created that includes different ions according to the ionization gases used. It has been found that, occasionally, portions of the generator itself (typically, of the electrode insulating holders) do participate in the ionization phenomenon to release ions into the plasma which originate from the chemical attack that the plasma carries out on the substances with which it comes in contact. An object of the present invention is to produce a stream of aluminum ions, specially useful in the microelectronics industry for the ion implantation of aluminum.